It is conventionally well known in the art that an oxidation product of an aromatic primary amine color developing agent couples with a color coupler, when a silver halide color light-sensitive material is subjected to the imagewise exposing as well as color developing, and forms dyes such as an indophenol, indoaniline, indamine, azomethine, phenoxyazine, phenazine and dyes similar to them, thus finally forming a dye image.
Couplers for forming a yellow dye image are, for example, acylacetanilide couplers Couplers for forming a magenta dye are, for example, pyrazolone, pyrazolobenzimidazole, pyrazolotriazole, and indazolone couplers Commonly used cyan dye image forming couplers are, for example, phenol and naphthol couplers
In particular, 1,2-pyrazolo-5-ones are commonly used as a coupler for forming a magenta dye image. Dyes formed from such couplers have a secondary absorption in the range around 430 nm in addition to a primary absorption around 550 nm; this secondary absorption in the blue spectral region causes color impurity which is a great disadvantage in color reproduction.
In addition, with the magenta coupler, a yellow stain due to light, heat and humidity in a non color formed portion is extremely greater than that of a cyan coupler or yellow coupler, incurring a disadvantage in improving image preservability.
Having satisfactorily improved secondary absorption making yellowish magenta color image as well as satisfactorily limited yellow stain, particularly excellent magenta couplers are pyrazolotriazoles described, for example, in U.S. Pat. No.s 3,725,067, Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Pat. O.P.I. Publication) Nos. 99437/1984, 162548/1984, and 171956/1984, Research Disclosure Nos 24220, 24230 and 24531.
The dyes formed from the pyrazolotriazole magenta couplers, described in these patent specifications and literatures, have significantly limited secondary absorption in the range around 430 nm, when compared to the dyes formed from the previously mentioned, 1,2-pyrazolo-5-ones having an anilino group in the 3-position. Accordingly, in addition to the significantly limited yellow stain in a non dye formed area induced by light, heat or humidity, a pyrazolotriazole magenta coupler shows satisfactory characteristics including satisfactory color reproducibility.
The dyes formed from pyrazolotriazole magenta couplers have excellent characteristics mentioned above which are fully exhibited, particularly, when they are incorporated into photographic color papers.
However, when compared to 1,2-pyrazo-5-one magenta couplers having an anilino group in the 3-position, the pyrazolotriazole magenta couplers incorporated into a silver halide emulsion disadvantageously show greater change in gradation after a long term storage
Various techniques for controlling gradation are known in the art. For example, as techniques for controlling gradation by controllingly preparing silver halide photographic light sensitive emulstions, teh rfollowing methods are known in teh art: a method for higher contrast performed by doping with metal such as rhodium as iridium ions during physical ripening; methods by controlling conditions for forming silver halide particles, such as the normal precipitation method for lower contrast, and the double-jet precipitation method for higher contrast; a method by deliverately selecting the pAg level, pH level, composition of silver halide particle in the course of particle formation; a method by changing condition for chemical sensitization. By using these methods independently or combinedly satisfactory gradation can be attained, however, most of these methods incur deterioration in other photographic properties such as sensitivity, fogging, reciprocity low failure, latent image stability, anti-pressure property, and production stability. Regardless of what method is used, it requires a great amount of effort to determine the conditions for satisfying all the criteria. Accordingly the commercial use of these techniques has limited effects.
To ensure color reproduction by color subtraction process, silver halide photographic light-sensitive materials such as a color photographic light-sensitive material for print incorporate a yellow coupler, magenta coupler and cyan coupler which are capable of forming, correspondingly, a yellow dye image, magenta dye image and cyan dye image by the coupling reaction with the oxidation product of an aromatic primary amine color developing agent Gradation modification may be achieved by deliverately selecting types of couplers and substituent groups contained in these couplers. However, such an arrangement also incurs change in other performance criteria such as tone of a dye image, and image preservability, making commercial use difficult.
An effective techniques to soften contrast in highlight portion by selecting a high boiling solvent for a coupler were described in Japanese Patent 0.P.I Publication No. 40550/1983. An effective technique for controlling gradation by selecting having a high boiling solvent for a coupler and by using a catecol derivative was described in Japanese Patent Application No. 213161/1984. However, these techniques are insufficient in preventing deterioration, in gradation balance indicated in the toe portion on the resultant characteristic curve, owing to the storage of the photographic material.
With the above mentioned pyrazolotriazone magenta coupler, as time elapses, gradation balance of silver chlorobromide green-sensitive emulsion layer containing the coupler is disturbed; more specifically, contrast at the toe portion on its characteristic curve softens, and each gradation balance at the toe portion on characteristic curve, respectively, of the red-scnsitive silver halide emulsion layer containing a cyan coupler, green-sensitive silver halide emulsion layer containing a magenta coupler, and blue-sensitive silver halide emulsion layer containing a yellow coupler is disturbed, often resulting in color print of unsatisfactory finish. Although slightly improving gradation balance, degree of improvement not yet satisfactory, an increased amount of a conventional surface active agent intensifies gradation deterioration attributable to the storage of photographic material and increases fogging. Accordingly, in order to ensure color print excelling in color reproduction and image preservability, it is essential to develop a technique for preventing softening in gradation at the toe portion on characteristic curve due to storage of photographic material, in particular, a technique for improving gradation balance indicated by the toe portion on the resultant characteristic curve, by utilizing property of the pyrazolotriazole magenta couplers mentioned above.
The present invention is based on the fact that a pyrazolotriazole magenta coupler or the like combined with a specific surface active agent provides color-balanced, sharp dye image free from gradation deterioration indicated by the poe portion on the resultant characteristic curve, where in the similar deterioration is attributable to storage of photographic material.